1. Field of the Invention
The present invention relates to an improvement of a voltage regulating system for controlling an output voltage of a direct current power supply that is utilized not only to supply electrical load on an automotive vehicle but to charge a storage battery installed in the automotive vehicle.
2. Description of Prior Art
A conventional voltage regulating system, for example, exemplified in the U.S. Pat. No. 3,469,168, comprises a first voltage sensing circuit connected to a storage battery for detecting a voltage thereof applied thereto by a direct current power source, a second voltage sensing circuit connected to said power source at another positive terminal, and a field control circuit connected to said first and second voltage sensing circuit and a field winding, whereby the battery voltage is controlled at a first preset level by the first voltage sensing circuit, and in the event that the first voltage sensing circuit disconnected from the battery, the battery voltage is controlled at a second preset level by the second voltage sensing circuit.
However it has a disadvantage that the second preset level is higher than the first one, whereby the battery may be overcharged or the life-time thereof may be shortened due to the overcharge.